From fff62e2ee8accf31bb5ac5abdb4c0636216cfd0e Mon Sep 17 00:00:00 2001
From: HcySunYang <HcySunYang@outlook.com>
Date: Wed, 21 Oct 2020 02:59:55 +0800
Subject: [PATCH] fix(runtime-core): non-stable Fragment should always unmount
 its children (#2445)

fix #2444
---
 .../__tests__/rendererOptimizedMode.spec.ts   | 42 +++++++++++++++++++
 packages/runtime-core/src/renderer.ts         |  7 +++-
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/packages/runtime-core/__tests__/rendererOptimizedMode.spec.ts b/packages/runtime-core/__tests__/rendererOptimizedMode.spec.ts
index 8b674b8a..24f496ca 100644
--- a/packages/runtime-core/__tests__/rendererOptimizedMode.spec.ts
+++ b/packages/runtime-core/__tests__/rendererOptimizedMode.spec.ts
@@ -475,4 +475,46 @@ describe('renderer: optimized mode', () => {
     render(null, root)
     expect(spy).toHaveBeenCalledTimes(1)
   })
+
+  // #2444
+  // `KEYED_FRAGMENT` and `UNKEYED_FRAGMENT` always need to diff its children
+  test('non-stable Fragment always need to diff its children', () => {
+    const spyA = jest.fn()
+    const spyB = jest.fn()
+    const ChildA = {
+      setup() {
+        onBeforeUnmount(spyA)
+        return () => 'child'
+      }
+    }
+    const ChildB = {
+      setup() {
+        onBeforeUnmount(spyB)
+        return () => 'child'
+      }
+    }
+    const Parent = () => (
+      openBlock(),
+      createBlock('div', null, [
+        (openBlock(true),
+        createBlock(
+          Fragment,
+          null,
+          [createVNode(ChildA, { key: 0 })],
+          128 /* KEYED_FRAGMENT */
+        )),
+        (openBlock(true),
+        createBlock(
+          Fragment,
+          null,
+          [createVNode(ChildB)],
+          256 /* UNKEYED_FRAGMENT */
+        ))
+      ])
+    )
+    render(h(Parent), root)
+    render(null, root)
+    expect(spyA).toHaveBeenCalledTimes(1)
+    expect(spyB).toHaveBeenCalledTimes(1)
+  })
 })
diff --git a/packages/runtime-core/src/renderer.ts b/packages/runtime-core/src/renderer.ts
index db47c15a..f0182c16 100644
--- a/packages/runtime-core/src/renderer.ts
+++ b/packages/runtime-core/src/renderer.ts
@@ -2038,7 +2038,12 @@ function baseCreateRenderer(
           false,
           true
         )
-      } else if (!optimized && shapeFlag & ShapeFlags.ARRAY_CHILDREN) {
+      } else if (
+        (type === Fragment &&
+          (patchFlag & PatchFlags.KEYED_FRAGMENT ||
+            patchFlag & PatchFlags.UNKEYED_FRAGMENT)) ||
+        (!optimized && shapeFlag & ShapeFlags.ARRAY_CHILDREN)
+      ) {
         unmountChildren(children as VNode[], parentComponent, parentSuspense)
       }